Users of battery chargers can benefit from the ability to charge more than one battery simultaneously without dividing the size of the current among the batteries. Examples of existing charging methods are described in U.S. Pat. Nos. 6,094,033 and 6,229,285, the entire contents of which are hereby incorporated by reference in their entirety.
Batteries have three intrinsic limitations during a charging cycle: maximum battery voltage, maximum battery temperature, and maximum allowable charging current. Exceeding any parameter can cause undercharging, overcharging, overheating or physical degradation, resulting in severely reduced battery life.
One method to rapidly charge a battery involves a discharge pulse from the battery being charged. This discharge could range from 2% to 10% of the charging pulse current amplitude. In large battery systems, the energy dissipated in this discharge pulse can be prohibitive to a practical battery charger for commercial and industrial use.
For example, for a 10 kW battery system, 10% of the energy would be dissipated. The resulting 1 KW would increase the cost of operating the charger by 10%. Moreover, the charger would require high power resistors, fans, heat sinks and other material in order to cool the product which would significantly increase the cost and size.